Goldman Sachs Group Inc plans to start disclosing more financial information to investors, including how much of its revenue comes from trading and investing its own money, a person familiar with the matter said.

The change comes after years of complaints from investors, analysts and others that the bank does not disclose enough information about exactly how it makes money.

Goldman has prepared a 63-page report after a more than eight-month internal review, the person said. The results of the review are set to be released publicly today, he added.

Many investors have complained that Goldman Sachs is a “black box” and that forecasting how its earnings will change over time is extremely difficult.

Goldman declined to comment.

The bank’s willingness to change is the latest sign of how financial reform and investor pressure are spurring banks to change the way they do business. Morgan Stanley said earlier yesterday it was planning to spin off a unit that trades the firm’s own money.

The bank’s Chief Executive, Lloyd Blankfein, reported the results of the report to about 470 of Goldman’s senior employees yesterday, the source said.